Apparatus for making visible magnetic fields by means of iron filings

ABSTRACT

An educational apparatus for displaying magnetic fields has a plurality of cells bordering each other in a flat unit with iron fillings therein and at least a transparent upper limiting surface on said cells. The present invention is concerned with an educational apparatus for making visible magnetic field.

Ilite Stes Uiwerstrom [54] APPARATUS FOR MAKING VISIBLE MAGNETIC FIELDSlBY MEANS OF IRON FILINGS [72] Inventor: Anders E. Ofwerstrom,Kullgardsvagen 21, 44300 Lerum, Sweden [22] Filed: July 1,1969

21 Appl.No.: 838,217

[30] Foreign Application Priority Data July 8, 1968 Sweden ..9360/68[52] US. Cl. ..35/19A [51] Int. Cl. ..G09b 23/18 [58] Field of Search..35/l9A,61,66; 46/236, 237,

[56] References Cited UNITED STATES PATENTS 1,549,197 8/1925 l-lanback..46/237 2,530,013 11/1950 Hanbeck ...46/237 3,426,453 2/1969 Dingwallet a1 ..35/61 Primary Examiner-Robert W. Michell Assistant Examiner-L.Anten AttorneyLinton & Linton [5 7] ABSTRACT An educational apparatusfor displaying magnetic fields has a plurality of cells bordering eachother in a flat unit with iron fillings therein and at least atransparent upper limiting surface on said cells.

The present invention is concerned with an educational apparatus formaking visible magnetic field.

2 Claims, 2 Drawing Figures Patented May 16, 1972 ATTORNEYS APPARATUS FOR MAKING VISIBLE MAGNETIC FIELDS lBY MEANS OF IRON FILINGS Theapparatus which has hitherto been used in the educational field ofphysics for illustrating magnetic fields have been very primitive. Inorder to prove and detect the appearance of such magnetic fields bymeans of small iron particles, so called iron filings or swarfs, it hasbeen common practice to spread a predetermined amount of such ironfilings upon a plate, whereupon the experiments have been carried out bybringing magnets, coils, solenoids or the like to act upon the ironparticles on the plate. It is a time consuming and cumbersome work touniformly spread the iron filings upon the plate and the teacher hastherefore been highly strained. In order to obtain good results it isnecessary that the iron particles are uniformly distributed over theeffective area of the plate. The more preparation of the plate has thusoften required so much time that it has been impossible to fulfill morethan one or two experiments during a lesson. After finishing theexperiments the teacher has had to gather together the iron filings andit has been impossible for him to prevent getting strongly stained andalso the magnets have been soiled by adhering particles, which have beenvery difficult to remove.

The main object of the present invention is consequently to eliminatethe above-mentioned drawbacks and to provide an apparatus, which may bemanufactured at low costs and by means of which various experiments maybe carried out without any previous preparations. The new apparatus isadapted for use merely by a slight shaking, which means that aconsiderable number of experiments may be carried out in the same timeperiod, which was earlier necessary for carrying out a singleexperiments, at the same time as the results will be considerably betterowing to the even distribution of the iron filings. To obtain these andother results the apparatus according to the invention is constructed inaccordance with the appended claims.

The attached drawing illustrates a preferred embodiment of the inventionand FIG. 1 shows a fragmentary section through the new apparatus whileFIG. 2 shows a portion of the same in a plan view.

According to the invention the iron filings for making visible themagnetic fields are divided into a plurality of small amounts, which areseparated from each other in that each amount is enclosed in a cellstructure. The cells illustrate together a magnetic field owing to thefact that the cells are located in close vicinity to each other and thatat least the upper limiting surface of each cell is transparent.

Practically this can be achieved in the manner shown in FIG. 1 and 2.From these figures the construction of an apparatus l is apparent, whichapparatus includes a base plate 2, preferably made from a transparentmaterial such as transparent acrylic plastic. Upon this base plate 2 isplaced a network 3, which preferably is made from textile fibers or froma similar, somewhat resilient material. In the spaces 5, which aregenerated by the net meshes, iron filings are introduced such that everymesh will contain a certain amount of iron filings, whereupon a upperplate 4, made from transparent material such as acrylic plastic, isapplied upon the net work 3. The unit is then sealed by gluing or thelike. Instead of a net work 3 it is of course possible to use a plate,provided with a plurality of openings or perforations, which serve thesame aim as the meshes. By means of this method an apparatus isobtained, in which iron filings are housed in cells, located in closevicinity to each other, the upper and lower limiting surfaces of whichare transparent. By using this apparatus the magnetic fields, generatedby magnets and the like, may be easily indicated by means of the ironfilings. There is of course no risk for soiling as the iron filings areenclosed in the cells.

The apparatus described and illustrated above is very advantageous inthat it is well suited for use in combination with an overheadprojector. Owing to the transparency of the apparatus the magneticfields may be easily illustrated by projection It has been proved thatthe network, which of course is pro ected at the same time as themagnetic field, has no disturbing effect at all, but it is possible tosubstantially avoid the visibility of the same by using a transparentmaterial. Magnets, solenoids, galvanometers and the like may be placedupon the unit to make different experiments.

The invention is not limited to the embodiment here shown and describedbut may be modified within the scope of the appended claims.

What I claim is:

1. Apparatus for making magnetic fields visible for educationalpurposes, comprising a substantially flat unit having an upper and lowersurface, a multitude of discrete cells adjacent each other within saidunit, a plurality of iron filings in each of said cells, said ironfilings are freely movable only within their respective cells, and atleast said units upper limiting surface of said cells being transparentso as to permit viewing of said iron filings.

2. Apparatus as claimed in claim 1, wherein a lattice structure madefrom a compressible material provides said cells, and both of said upperand lower limiting surfaces covering said lattice structure aretransparent to provide said flat unit.

1. Apparatus for making magnetic fields visible for educationalpurposes, comprising a substantially flat unit having an upper and lowersurface, a multitude of discrete cells adjacent each other within saidunit, a plurality of iron filings in each of said cells, said ironfilings are freely movable only within their respective cells, and atleast said units upper limiting surface of said cells being transparentso as to permit viewing of said iron filings.
 2. Apparatus as claimed inclaim 1, wherein a lattice structure made from a compressible materialprovides said cells, and both of said upper and lower limiting surfacescovering said lattice structure are transparent to provide said flatunit.